1. Field of the Invention
The present invention relates to assistance with the preparation and with the following of a flight plan taking account of diversion airports and their joining trajectories in respect of aircraft provided with a flight management computer effecting the plotting of a flight plan on the basis of a trajectory skeleton introduced by the crew and consisting of waypoints associated with various constraints on heading, speed, altitude, etc.
2. Description of the Related Art
A crew pilots an aircraft by way of various equipment installed on board the aircraft and termed flight equipment. Such flight equipment is distributed according to three levels as a function of its position in the chain of actuation of the moveable surfaces and of the engines of the aircraft. The first level consists of the flight commands acting directly on the actuators of the movable surfaces and engines. They allow manual piloting. The second level consists of the automatic pilot and/or flight director which act on the flight commands, directly for the automatic pilot and by way of the pilot for the flight director, and which allow the pilot to slave the aerodyne to a quantity related to the trajectory of the aircraft: attitude, heading, slope, route, altitude, speed, deviations with respect to routes, etc. The third level consists of the flight management computer which acts on the automatic pilot and/or flight director and which allows the pilot to plot a flight plan and to more or less automatically follow the flight plan adopted.
The plotting of a flight plan by a flight management computer is done on the basis of a trajectory skeleton introduced by the crew and consisting of waypoints associated with various constraints on heading, altitude, speed, etc. By applying preprogrammed construction rules, the flight management computer constructs a route to be followed, on the basis of a chaining together of segments linking the waypoints together in pairs from the departure point to the arrival point and of circular arc transitions at the level of the waypoints for the changes of heading between segments.
During the preparation and the plotting of a flight plan, the crew of an aircraft have a duty to ensure maximum safety of the mission by taking account of the most common vagaries that may require an unscheduled stopover or a diversion such as engine problems at takeoff dealt with according to an EOSID procedure (the acronym standing for the expression “Engine Out Standard Instrument Departure”), engine problems while cruising that give rise for twin-engines to restrictions of movement that are imposed by an ETOPS procedure (the acronym standing for the expression “Extended Twin OperationS”), problems of lack of fuel, of unexpected change of airport runway in use, of unavailability of the destination airport, etc.
It is known, in particular through American patents U.S. Pat. Nos. 5,842,142, and 5,398,186 to facilitate the work of a crew in taking account of a diversion airport in case of closure of the destination airport or of emergency situation, by calling upon an onboard database or one which is accessible by radio transmission from the aircraft, cataloging the diversion landing fields, upon an interface for programming the flight management computer termed the MCD (the acronym standing for the expression “Multipurpose Control Display”) displaying, on request by the crew, a list of diversion airports ranked as a function of their proximities to the current position of the aircraft and, after selection, by the crew, of one of the diversion airports proposed, a proposal of a choice of trajectories for joining the diversion airport selected on the basis of the current position of the aircraft, which are calculated by the flight management computer.
This aid alleviates the work of a crew in the case of an incident in the course of a flight justifying a diversion but it demands that the crew program the flight computer while at the same time having to ward off the consequences of the incident that has occurred.
It is also known, in particular through American patent U.S. Pat. No. 6,519,527, to facilitate the plotting by the crew of an aircraft of a flight plan complying with an ETOPS procedure, by calling upon an onboard database or one accessible by radio transmission cataloging the landing fields placed in proximity to the route of the aircraft between its departure point and its destination, and by having the flight management computer determine a band linking the departure point of the aircraft to its destination point, in which band the trajectory of the flight plan must be situated in order for the aircraft to remain constantly at a distance from an emergency airport cataloged in the database, which is less than that prescribed by the ETOPS procedure.